A CORRUGATED ADDITION FOR INCREASED DAMPING IN FLEXURE.
Technical rept. for 15 Jun 60-15 Jun 64,
MINNESOTA UNIV MINNEAPOLIS
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Various types of surface additions which incorporate viscoelastic adhesive layers for high damping are reviewed and their limitations discussed. A new type of configuration having the general form of a corrugation is shown to be capable of dissipating large damping energy through cyclic shear in a viscoelastic adhesive layer. Expressions are derived for the energy dissipation in one particular form of this configuration. The optimum geometry for maximum damping is discussed with respect to several critical parameters. Corrugated configurations were constructed and tested to check the theory. Satisfactory agreement was found between the experimental results and the values predicted by the theory for shear strain in the viscoelastic layer, for the large increase in damping associated with the adhesive shear mechanism, and for the optimum thickness of the viscoelastic adhesive for maximum damping. As an indication of the increase in damping realized through the corrugated addition approach, the loss coefficient of an aluminum beam at a cyclic stress of 4000 psi was increased from approximately 0.01 to 0.2 by the corrugated addition. Author